Each year, people are diagnosed with over one hundred diseases that are classified as different types of cancer, the second leading cause of death in the United States. In 1999 alone, over 1.2 million people were affected by cancer. Malignant tumors are most dangerous when they metastasize or spread throughout the body. This occurs when cancerous cells from a tumor enter the bloodstream and invade into tissues and organs. Recently, our laboratory found that inhibition of the Na,K pump results in increased intracellular sodium in kidney epithelial cells, which induces a signal transduction pathway leading to metastasis. Differential display screening revealed that one of the key players in this pathway is the MDM2 oncoprotein, which is responsible for degradation of p53, a tumor suppressor protein. The main goal of this research is to understand the significance of the induction of AMID upon inhibition of the sodium pump and to characterize the consequence of MDM2 overexpression in polarized kidney epithelial cells.